Photovoltaic energy is becoming a very significant power source for several reasons. Fossil fuels are becoming scarcer, and hence more expensive, every day. Furthermore, the burning of fossil fuels releases pollutants, including greenhouse gases which contribute to problems of global warming. Also, recent events have raised questions as to the safety and cost-effectiveness of nuclear power. For these reasons, traditional energy sources have become far less attractive. Photovoltaic energy, on the other hand, is inherently non-polluting, safe and silent. In addition, recent advances in photovoltaic technology have significantly increased the efficiency and decreased the cost of such devices.
For example, it is now possible to manufacture large area silicon and/or germanium alloy materials which manifest electrical, optical, chemical, and physical properties equivalent, and in many instances superior to, their single crystalline counterparts. Layers of such alloys can be economically deposited at high speed over relatively large areas and in a variety of stacked configurations. Such alloys readily lend themselves to the manufacture of low cost photovoltaic devices. Examples of particular fluorinated semiconductor alloy materials having significant utility in fabrication of photovoltaic devices are described in U.S. Pat. No. 4,226,898 and U.S. Pat. No. 4,217,364, both invented by Ovshinsky et al, the disclosures of which are incorporated herein by reference.
Thin film silicon and/or germanium alloy materials have found many applications from incorporation in calculators to large area grids for providing power to either homes or neighborhoods or even whole communities.
Previous attempts at incorporating photovoltaic material as a roofing surface has involved prefabricated panels with single crystalline photovoltaic cells mounted on the panels. The panels are assembled together in a standard batten-seam roof construction. What is needed is an economical and cost-effective system for constructing a panel or roof structure on site combining the flexibility of thin film photovoltaic materials and the semi-flexibility of sheets of roofing construction material such as galvanized steel to form a coil of thin film photovoltaic material laminated onto a galvanized steel substrate. What is also needed is a laminate that can be formed into photovoltaic roofing panels on site or off site and installed and connected together to form a roof assembly.